This invention relates generally to beams for construction and more particularly to fabricated wooden beams.
As first-generation forests are used up and replanted, the second-generation trees do not increase in trunk diameter uniformly with time. These second-generation trees grow relatively quickly to a certain trunk diameter and beyond that size, growth is slower. Therefore, the optimum growing time before harvest produces narrower timber for use in fashioning beams, stringers or the like. Prior art discloses certain methods of mechanically fastening two or more continuous narrower beams together to form a single wider beam of the desired width previously readily available from first-generation timber. One such method, employed by Simplex Development Corporation in their KOR-JOIST, is a plurality of closely-spaced unique fasteners driven into both sides of the beam parallel to one another and at an acute angle to the seam to span the joint or seam between any two longitudinal members. Only full-length longitudinal members are generally used, and where beam width requirements exceed a certain amount, three or more full-length members are so joined together.
Another method of beam fabrication is used by Automated Construction Equipment, Inc., in their W-JOIST. This fabricated beam design eliminates a significant portion of the length of the center longitudinal member in a three-member beam. In place of the eliminated center member portions are one or more unique "W"-shaped truss plates driven into both ends of the outer members. However, these "W"-shaped truss plates are expensive and, additionally, beams constructed thusly may only be varied in length a certain amount by cutting. No cuts may be made through the expanse of abutting "W"-shaped truss plates. Additionally, the portions of the center member which are required are of sufficient length so as to represent a significant portion of the overall wood material cost and must also be truss plated or stapled to the outer members by means separate from the "W" truss plates.
The present invention discloses a fabricated wooden beam constructed of two or more full-length members spaced apart to achieve the desired overall beam width by short spacer blocks of typically otherwise scrap wood. These pieces are held together in a secure useful beam or stringer by a plurality of conventional truss plates nailed or pressed into place, one diagonally across each spacer block and into the longitudinal members which the spacer block is separating. These truss plates are so placed in pairs, one on each side of the beam, such that the parallel diagonal alignment of the truss plates on one side of the beam crosses those placed on the opposite side of the beam. As the larger one-piece beams are depleted in the forests, these wider fabricated beams will become less expensive in both material cost and in manufacturing labor costs and afford versitility in available cutting lengths.